Fluid dynamic foil with Coanda energizer
Presented is an improved concept airfoil, or more properly called fluid dynamic foil, that promises coefficients of lift several times better than present day airfoils or hydrofoils. This is accomplished by use of a rotary Coanda fluid accelerator that is part of the boundary of a high camber or fat airfoil shape. Acceleration of oncoming fluids over the low static pressure side of the airfoil by the rotary element not only decreases the static pressure thereby increasing lift but also improves flow characteristics over the low static pressure side of the airfoil which reduces or eliminates flow separation and its associated turbulent drag effects. Alternative ways to eliminate the flow separation are also presented as well as are ways to control the angle of attack of the airfoil. The concept presented is applicable to aircraft wings, rotary wings such as used on helicopters, hydrofoils, wind and water turbine blades, and the like.
Airfoils are, of course, essential to flight through air and hydrofoils through water. A better name that works in any fluid medium would be Fluid Dynamic Foils (FDF) and that name is used herein to signify use of foils in any fluid medium. Much work has been done in the development of airfoils over the years. One of the more interesting developments was the early work on high camber or fat airfoils done in the thirties. These high camber airfoils demonstrated Coefficients of Lift (CL) of 4 to 4.5 at angle of attacks (∝) of 5-10 degrees when enhanced by Boundary Layer Control (BLC). This compares to a CL of only about 1.6 at the same ∝'s for present day airfoils. This would indicate that use of high camber airfoils with BLC would result in about 2.5 times the CL of present day airfoils or hydrofoils.
A good source of background in this area is from
What is presented in the instant invention is a means to accelerate fluids over a FDF such that even higher velocities, and hence lower static pressures and higher CL's, over an airfoil's or hydrofoil's upper surface than those demonstrated with the high chamber airfoils in the earlier work. This is done by means of a forward disposed rotary element that is at least part of the FDF's shape. Rotation of the rotary element, by means of the well known Coanda Effect, accelerates fluid over the upper surface of the FDF. This acceleration of fluids over the upper surface of the FDF will result in even lower static pressures and hence a higher CL than demonstrated heretofore in the prior art.
It is possible that no BLC will be required when the Coanda Effect rotary element is employed. However, the rotary element may be utilized to supply the work to accomplish BLC. In such instance the rotary element does the fluid energizing required for BLC during its normal rotation. Ways to accomplish changes in ∝ are possible by either rotating portions of the FDF around the rotary element or by rotating the entire FDF including the rotary element as a unit.
SUMMARY OF THE INVENTIONWith the foregoing in mind, it is a principal object of the present invention to provide an improved fluid dynamic foil that offers greater efficiencies than the prior art by having a rotary element to add acceleration to fluids traveling over the low pressure side of the fluid dynamic foil thereby reducing the static pressure further and enhancing the coefficient of lift of the fluid dynamic foil and whereby said rotary element makes up-part of the boundary of the fluid dynamic foil.
A related object of the invention is- that the rotary element be disposed proximal a forward end of and wherein an aft end of said fluid dynamic foil completes at least a majority of the trailing end of a generally elongated foil shape.
A related object of the invention is that the rotary element may be fully or partially driven by artificial means that may be in the form of a powering rotatable device.
A further object of the invention is that the rotary element may be fully or partially driven by rotational energy supplied by a fluid turbine where said fluid turbine obtains at least part of its energy from fluid passing by the fluid dynamic foil.
Yet another object of the invention is that said improved fluid dynamic foil, including its rotary element, have a maximum camber as measured in percent of chord length of at least seven percent.
A further related object of the invention is that said fluid dynamic foil, including its rotary element, have a maximum camber as measured in percent of chord length of at least nine percent.
Yet another related object of the invention is that said fluid dynamic foil, including its rotary element, have a maximum camber as measured in percent of chord length of at least eleven percent.
Another object of the invention is that fluid energized by the rotary element may be directed through a fluid passageway with said fluid passageway discharging fluid through an exit opening in the low static pressure surface.
A directly related object of the invention is that said exit opening in the low static pressure surface of the fluid dynamic foil be disposed, at least in its majority, aft of mid-span of the improved fluid dynamic foil.
Yet another object of the invention is that a fluid passageway may be, at least in its majority, positioned upstream of a fluid labyrinth seal.
A further object of the invention is that a fluid passageway may connect the low static pressure surface and a fluid energizing chamber positioned proximal the rotary element thereby aspirating fluid from the low static pressure surface.
Still another object of the invention is that an aft portion of the fluid dynamic foil may rotate about the rotary element.
A directly related object of the invention is that power for rotation of an aft portion of the fluid dynamic foil may be supplied by artificial means.
A further object of the invention is that trim control of the fluid dynamic foil may be accomplished by flap-like devices.
BRIEF DESCRIPTION OF THE DRAWINGS
The figures presented in this application normally show airfoils or FDF's horizontally oriented. It is to be realized that it is within the spirit and scope of the invention that they may be oriented vertically or at any other angle including a rotation of 180 degrees from the orientation of the figures as presented.
Referring back to the discussion of
It is important to note the fluid flow arrows 31 forward of the rotary element 30. These show the fluid approaching the rotary element 30 to be induced to turn upward rather than divided more evenly top and bottom as was seen in the high camber prior art airfoils of
While the invention has been described in connection with a preferred and several alternative embodiments, it will be understood that there is no intention to thereby limit the invention. On the contrary, there is intended to be covered all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims, which are the sole definition of the invention.
Claims
1. In an improved fluid dynamic foil, the improvement comprising:
- a rotary element disposed proximal a forward end of and comprising part of a boundary of the fluid dynamic foil, wherein an aft end of said fluid dynamic foil completes at least a majority of the trailing end of a generally elongated foil shape, and wherein rotation of said rotary element aids in accelerating fluids over a low static pressure surface disposed opposite a high static pressure surface of the fluid dynamic foil thereby providing a resultant force on the fluid dynamic foil that is in a direction from the high static pressure surface to the low static pressure surface.
2. The improved fluid dynamic foil of claim 1 wherein said rotary element is, at least partially, driven by a rotatable drive device.
3. The improved fluid dynamic foil of claim 1 wherein said rotary element is, at least partially, driven by a fluid driven turbine like device that is coupled to the rotary element.
4. The improved fluid dynamic foil of claim 1 wherein said improved fluid dynamic foil, including its rotary element, has a maximum camber as measured in percent of chord length of at least seven percent.
5. The improved fluid dynamic foil of claim 1 wherein said improved fluid dynamic foil, including its rotary element, has a maximum camber as measured in percent of chord length of at least nine percent.
6. The improved fluid dynamic foil of claim 1 wherein said improved fluid dynamic foil, including its rotary element, has a maximum camber as measured in percent of chord length of at least eleven percent.
7. The improved fluid dynamic foil of claim 1 wherein fluid energized by the rotary element is directed through a fluid passageway and said fluid passageway discharges fluid through an exit opening in the low static pressure surface.
8. The improved fluid dynamic foil of claim 7 wherein said exit opening in the low static pressure surface is disposed, at least in its majority, aft of mid-span of the improved fluid dynamic foil.
9. The improved fluid dynamic foil of claim 7 wherein energized fluid supplied to said fluid passageway comes from, at least in its majority, a fluid energizing chamber positioned proximal the rotary element and upstream of a fluid labyrinth seal.
10. The improved fluid dynamic foil of claim 1 wherein a fluid passageway connects the low static pressure surface and a fluid energizing chamber positioned proximal the rotary element thereby aspirating fluid from the low static pressure surface.
11. The improved fluid dynamic foil of claim 1 wherein an aft portion of the fluid dynamic foil rotates about the rotary element.
12. In an improved fluid dynamic foil, the improvement comprising:
- said improved fluid dynamic foil having a rotary element proximal its forward portion wherein rotation of said rotary element increases fluid velocity over the low static pressure side of the fluid dynamic foil thereby decreasing static pressure further resulting in a higher coefficient of lift for the fluid dynamic foil and said fluid dynamic foil having a maximum camber as measured in percent of chord length of at least seven percent.
13. The improved fluid dynamic foil of claim 12 wherein said rotary element is, at least partially, driven by a rotatable drive device.
14. The improved fluid dynamic foil of claim 12 wherein said rotary element is, at least partially, driven by a fluid driven turbine like device that is coupled to the rotary element.
15. The improved fluid dynamic foil of claim 12 wherein said improved fluid dynamic foil, including its rotary element, has a maximum camber as measured in percent of chord length of at least nine percent.
16. The improved fluid dynamic foil of claim 12 wherein said improved fluid dynamic foil, including its rotary element, has a maximum camber as measured in percent of chord length of at least eleven percent.
17. The improved fluid dynamic foil of claim 12 wherein fluid energized by the rotary element is directed through a fluid passageway and said fluid passageway discharges fluid through an exit opening in the low static pressure surface.
18. The improved fluid dynamic foil of claim 17 wherein said exit opening in the low static pressure surface is disposed, at least in its majority, aft of mid-span of the improved fluid dynamic foil.
19. The improved fluid dynamic foil of claim 12 wherein a fluid passageway connects the low static pressure surface and a fluid accelerating chamber positioned proximal the rotary element thereby aspirating fluid from the low static pressure surface..
20. In an improved fluid dynamic foil, the improvement comprising:
- said improved fluid dynamic foil having a rotary element proximal its forward portion wherein rotation of said rotary element increases fluid velocity over the low static pressure side of the fluid dynamic foil thereby decreasing static pressure further resulting in a higher coefficient of lift for the fluid dynamic foil and wherein fluid energized by the rotary element is directed through a fluid passageway and said fluid passageway connects with an opening in the low static pressure surface.
Type: Application
Filed: Jan 12, 2006
Publication Date: Jul 12, 2007
Inventor: Donald Burg (Miami, FL)
Application Number: 11/330,845
International Classification: B64C 3/50 (20060101);